In studies on the basic mechanisms underlying the occurrence of hyperbilirubinemia at altitude it was found that the main factors are increased destruction of erythrocytes associated with severe polycythemia (hematocrit above 68%), increased intravascular hemolysis due to increased blood viscosity, and inability of the liver to handle increased level of bilirubin. Studies are being conducted on physiological and biochemical changes after exposure to cigarette smoke in rats at rest and after exercise. Studies are being conducted on the effects of hypoxia on reproductive function prior to blastocyst implantation and on male reproductive function in mice.